SAT-104 A rare drug toxicity as an unexpected finding on kidney biopsy

Abstract

Renal biopsy in cases of unexplained renal failure can occasionally show findings which may not be directly relevant to the clinical scenario, but which nonetheless has a bearing on the long term follow up and management, in the form of addition of a therapeutic regimen, or preventing further exposure to an offending drug. A 35 year old Emirati gentleman was admitted to the hospital on 25th of April 2019 with complaints of left flank pain, dysuria, increased urination, headache and mildly confused state. Past history was significant for bipolar affective disorder for which he was on therapy from a different hospital with Risperidone, Clonazepam and Procyclidine. There was no history of renal disease. Clinical examination revealed an individual who was disoriented in time and place, and hypertension, with rest of the examination findings being unremarkable. Investigations revealed anemia, bland urine sediments, azotemia, hyponatremia, low serum and urine osmolality and normal sized kidneys on ultrasound with mild increase in cortical echogenicity. He was diagnosed with hyponatremia and unexplained renal failure. The serum sodium was corrected with 3% saline and water restriction, and a renal biopsy was performed The biopsy returned a picture of mild mesangial expansion (Image 1), foci of acute kidney injury, chronic interstitial nephritis and microcystic dilatation of the tubules ( Image 2), one of the lesions seen in chronic lithium toxicity. On further enquiry with the patient, a remote history of Lithium consumption was obtained but the duration was unknown. It was stopped completely 3 years ago. During clinic follow up, urine output and Sodium was maintained normal with fluid restriction alone. The renal functions showed an improvement from the time of admission, and since has remained stable.View Large Image Figure ViewerDownload Hi-res image Download (PPT) Lithium nephrotoxicity spans a spectrum, from concentration defects to nephrogenic diabetes insipidus, chronic interstitial nephritis and rare glomerular involvement. Duration of treatment and cumulative dose are the determinants of renal toxicity. Careful monitoring and early withdrawal are the key to limiting damage, as a creatinine more than 2.5mg/dl at biopsy is a risk for progression to ESRD. In those with early signs of toxicity, but in whom Lithium would be necessary, a concurrent use of Amiloride could limit the damage.